1. Field of the Invention
The present invention relates to multi-hop communication that forwards data to a wireless communication apparatus via wireless relay communication apparatuses.
2. Description of the Related Art
When a wireless communication terminal for performing conventional relay (to be referred to as a wireless relay communication terminal hereinafter) relays data, the address of a final wireless relay communication terminal in a relay system is described in an address field of a frame to be transmitted, in addition to the address of a wireless relay communication terminal as the direct transmission destination of the frame (e.g., Japanese Patent Nos. 3774426 and 3774469, and W. Steven Conner et al., “IEEE802.11s Tutorial, Overview of the Amendment for Wireless Local Area Mesh Networking,” [online, IEEE802 Meeting Tutorial Reference], Nov. 13, 2006, IEEE802, Internet <URL: http://www.ieee802.org/802_tutorials/index.htm “Tutorial #1 (6:30 pm):802.11s:WLAN Mesh Networking”>). A method is described by which if no routing information has been established when transmitting the frame to the final wireless relay communication terminal, a broadcast address is set in the field for the address of the wireless relay communication terminal as the direct transmission destination, thereby delivering the frame to the final wireless relay communication terminal (e.g., Japanese Patent No. 3774426 or 3774469).
There is also a method of relaying forwarding data by encapsulating such data (e.g., JP-A. 2006-279168 (KOKAI)), and a method of adding an address on a relay route to a frame header (e.g., JP-A. No. 2006-140943 (KOKAI)).
Unfortunately, the above-mentioned conventional techniques are based on the assumption that the final wireless relay terminal is determined, and hence cannot relay data if the terminal is undetermined. Also, none of the conventional techniques describe a method of controlling data relay in a situation in which a communication terminal connecting to the final wireless relay communication terminal is the final destination terminal of data, and the final wireless relay communication terminal is changed because, e.g., the destination address terminal also connects to another wireless relay communication terminal. If a wireless relay communication terminal that is in power save mode exists, it is difficult to expect that routing information will be properly updated in the wireless relay system. Accordingly, the wireless relay will not function in the real system.